Heretofore, as a vehicle device control system, there has been known, as disclosed in JP2000-104429A, a system that controls changeovers of locked/unlocked states of individual doors on the basis of a collated result of an ID code based on mutual radio communications between a portable electronic key (portable device) and a vehicle-side unit. Besides, in a case where a holder of the portable device is inside a vehicle compartment, a release of steering lock and a start of an engine are permitted.
The vehicle-side unit is configured by outside transmitters, an inside transmitter, and a rear transmitter inside a luggage compartment, which transmit request signals to the portable device, a receiver which receives a response signal from the portable device, and a main control ECU which controls vehicle devices such as the doors, on the basis of the results of transmissions and receptions to and from the portable device. The outside transmitters, the inside transmitter and the rear transmitter have communication areas in which they are capable of the mutual communications with the portable device, in predetermined ranges around a vehicle, inside the vehicle compartment and inside the luggage compartment, respectively. Thus, it is possible to sense that a holder of the portable device approaches the vehicle, or that the holder gets on or off the vehicle.
In a case, for example, where the holder of the portable device has approached the vehicle in order to get on the vehicle and where he/she has entered the communication area of the outside transmitter, the portable device transmits the response signal containing its ID code, to the vehicle-side unit in response to a request signal. Upon determining that the ID code acquired from the portable device satisfies a predetermined relation such as the agreement thereof with a registered ID code, the vehicle-side unit gives a door lock controller being the vehicle device, a control signal so as to unlock the corresponding door. When the holder of the portable device has gotten on the vehicle, the communication area of the outside transmitter with the portable device shifts from outside the vehicle into the vehicle compartment. Then, the vehicle-side unit releases the steering lock and permits the start of the engine as the controls of the vehicle devices, on the basis of the collated result of the ID code.
Meanwhile, the communication area of the rear transmitter is sometimes expanded so as to cover a partial region inside the vehicle compartment, whereby the vehicle-side unit can perform the mutual communications with the portable device, in the whole region inside the vehicle compartment by the inside transmitter and the rear transmitter. In this case, when the collation of the ID code has proceeded favorably by the mutual communications between the rear transmitter and the portable device, the main control ECU performs the controls so as to release the steering lock and to permit the engine start.
In addition, it is sometimes desired to use the vehicle in a state where the portable device and a bag or the like baggage put into the luggage compartment are collected, and where the portable device is placed in the luggage compartment. Also in this case, as in the above case, the steering lock is released and the engine start is permitted when the collation of the ID code has proceeded favorably by the mutual communications between the rear transmitter and the portable device.
It is problematic, however, to simply permit the engine start on the basis of the collated result of the ID code based on the mutual communications between the luggage-compartment transmitter and the portable device. More specifically, when the luggage compartment door is brought into its open state, the shield of electric waves is removed, and the communication area based on the rear transmitter is expanded outside the vehicle. As a result, even when the portable device exists outside the vehicle, the start of the engine is possible. Then, in a case, for example, where the authorized holder of the portable device is performing a loading or unloading operation with the luggage compartment door opened, the engine might be started by a third party, and the security of the vehicle is apprehended.